U.S. patent application number 11/833380 was filed with the patent office on 2008-03-13 for electrophotographic photoreceptor.
This patent application is currently assigned to KONICA MINOLTA BUSINESS TECHNOLOGIES, INC.. Invention is credited to Hirofumi HAYATA, Masahiko KURACHI, Kunihiro OGURA.
Application Number | 20080063960 11/833380 |
Document ID | / |
Family ID | 39170116 |
Filed Date | 2008-03-13 |
United States Patent
Application |
20080063960 |
Kind Code |
A1 |
HAYATA; Hirofumi ; et
al. |
March 13, 2008 |
ELECTROPHOTOGRAPHIC PHOTORECEPTOR
Abstract
An electrophotographic photoreceptor comprising a photosensitive
layer and a protective layer is disclosed. The protective layer
comprises a resin which is prepared by allowing at least two
acrylic or methacrylic compounds to react, and the acrylic or
methacrylic compounds include a minimum acryloyl equivalent
compound having minimum acryloyl equivalent and a maximum acryloyl
equivalent compound having maximum acryloyl equivalent and
relationships 1) and 2) are satisfied; 100.ltoreq.maximum acryloyl
equivalent-minimum acryloyl equivalent.ltoreq.400 1)
0.1.ltoreq.weight of minimum acryloyl equivalent compound/weight of
maximum acryloyl equivalent compound.ltoreq.1.6. 2)
Inventors: |
HAYATA; Hirofumi; (Tokyo,
JP) ; KURACHI; Masahiko; (Tokyo, JP) ; OGURA;
Kunihiro; (Tokyo, JP) |
Correspondence
Address: |
LUCAS & MERCANTI, LLP
475 PARK AVENUE SOUTH, 15TH FLOOR
NEW YORK
NY
10016
US
|
Assignee: |
KONICA MINOLTA BUSINESS
TECHNOLOGIES, INC.
Tokyo
JP
|
Family ID: |
39170116 |
Appl. No.: |
11/833380 |
Filed: |
August 3, 2007 |
Current U.S.
Class: |
430/58.05 ;
430/132; 430/66 |
Current CPC
Class: |
G03G 5/14795 20130101;
G03G 5/14734 20130101; G03G 5/14786 20130101; G03G 5/1473 20130101;
G03G 5/14791 20130101 |
Class at
Publication: |
430/58.05 ;
430/132; 430/66 |
International
Class: |
G03G 5/04 20060101
G03G005/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 11, 2006 |
JP |
2006-245364 |
Claims
1. An electrophotographic photoreceptor comprising an electrically
conductive support having thereon a photosensitive layer and a
protective layer in that order, wherein the protective layer
comprises a resin which is prepared by allowing at least two
acrylic or methacrylic compounds to react, and one of the acrylic
or methacrylic compounds is a minimum acryloyl equivalent compound
having a minimum acryloyl equivalent and another of the acrylic or
methacrylic compounds is a maximum acryloyl equivalent compound
having a maximum acryloyl equivalent, the minimum acryloyl
equivalent being different from the maximum acryloyl equivalent,
and relationships 1) and 2) are satisfied; 100.ltoreq.maximum
acryloyl equivalent-minimum acryloyl equivalent.ltoreq.400 1)
0.1.ltoreq.weight of minimum acryloyl equivalent compound/weight of
maximum acryloyl equivalent compound.ltoreq.1.6, 2) wherein
acryloyl equivalent of an acrylic or methacrylic compound is
(molecular weight of the acrylic or methacrylic compound)/(number
of acryloyl or acryloyl groups of the acrylic or methacrylic
compound).
2. The electrophotographic photoreceptor of claim 1, wherein the
relationships 2') is satisfied; 0.1.ltoreq.weight of minimum
acryloyl equivalent compound/weight of maximum acryloyl equivalent
compound.ltoreq.0.5. 2')
3. The electrophotographic photoreceptor of claim 1, wherein the
number of acryloyl or methacryloyl groups of the minimum acryloyl
equivalent compound is at least 4.
4. The electrophotographic photoreceptor of claim 1, wherein the
number of acryloyl or methacryloyl groups of the maximum acryloyl
equivalent compound is 2.
5. The electrophotographic photoreceptor of claim 1, wherein the
protective layer has a thickness of 0.2-10 .mu.m.
6. The electrophotographic photoreceptor of claim 1, wherein the
protective layer has a thickness of 0.5-6 .mu.m.
7. The electrophotographic photoreceptor of claim 1, wherein the
protective layer contains a filler.
8. The electrophotographic photoreceptor of claim 1, wherein the
protective layer contains a lubricant.
9. The electrophotographic photoreceptor of claim 8, wherein the
lubricant is fluorine containing resin particles.
10. The electrophotographic photoreceptor of claim 1, further
comprising an inter layer between the electrically conductive
support and the photosensitive layer.
11. The electrophotographic photoreceptor of claim 1, wherein the
inter layer is composed of a polyamide resin.
12. The electrophotographic photoreceptor of claim 1, wherein the
inter layer has a thickness of 0.1-15 .mu.m.
13. The electrophotographic photoreceptor of claim 1, wherein the
photosensitive layer comprises a charge generating layer and a
charge transporting layer.
14. A method for preparing an electrophotographic photoreceptor of
claim 1, comprising steps of; forming a photosensitive layer on an
electrically conductive support, and coating a composition
containing at least two acrylic or methacrylic compounds dissolved
in a solvent on the photosensitive layer, and exposing the coated
composition to actinic radiation to form a protective layer,
wherein one of the acrylic or methacrylic compounds is a minimum
acryloyl equivalent compound having a minimum acryloyl equivalent
and another of the acrylic or methacrylic compounds is a maximum
acryloyl equivalent compound having a maximum acryloyl equivalent,
the minimum acryloyl equivalent being different from the maximum
acryloyl equivalent, and relationships 1) and 2) are satisfied;
100.ltoreq.maximum acryloyl equivalent-minimum acryloyl
equivalent.ltoreq.400 1) 0.1.ltoreq.weight of minimum acryloyl
equivalent compound/weight of maximum acryloyl equivalent
compound.ltoreq.1.6, 2) wherein acryloyl equivalent of an acrylic
or methacrylic compound is (molecular weight of the acrylic or
methacrylic compound)/(number of acryloyl or acryloyl groups of the
acrylic or methacrylic compound).
15. The method of claim 14, wherein the coating composition further
contains a radical polymerization initiator.
16. The method of claim 11, wherein the radical polymerization
initiator is a photopolymerization initiator or thermal
polymerization initiator.
17. The method of claim 11, wherein an amount of the radical
polymerization initiator is 0.1-20% by weight with respect to the
total weight of the (meth)acrylic compounds.
18. The method of claim 13, wherein an amount of the radical
polymerization initiator is 0.5-10% by weight with respect to the
total weight of the (meth)acrylic compounds.
19. The method of claim 12, wherein the steps further comprises
drying between the steps of coating and exposing.
Description
[0001] This application is based on Japanese Patent Application No.
2006-245364 filed on Sep. 11, 2006, in Japanese Patent Office, the
entire content of which is hereby incorporated by reference.
FIELD
[0002] The present invention relates to an electrophotographic
photoreceptor.
BACKGROUND OF THE INVENTION
[0003] An electrophotographic receptor is required to exhibit
necessary photographic speed, electric characteristics and optical
characteristics according to employed electrophotographic
processes. Further, in such a photoreceptor, which is, repeatedly
employed many times, the surface layer of the photoreceptor, namely
the layer furthest apart from the support is subjected to
application of external electrical and mechanical forces such as
charging, exposure, development, image transfer, or cleaning,
whereby durability against those is demanded. Specifically,
durability against surface abrasion and scratching due to sliding
and surface degradation due to ozone and nitrogen oxides formed
during charging is required. On the other hand, there are problems
of adhesion of toner onto the surface layer due to repetition of
development and cleaning of toner and conversion to accumulation of
foreign matter. In order to overcome those, it is sought to enhance
cleaning properties of the surface layer.
[0004] In order to realize characteristics demanded for the surface
layer as described above, trials have been conducted in which a
protective layer composed of curable resin as a main component is
provided. For example, proposed is a protective layer of which
resistance is controlled via addition of metal oxides as a
conductive powder (refer, for example, to Patent Document 1). Main
objectives of dispersion of metal oxides into the protective layer
for an electrophotographic photoreceptor include minimization of an
increase on the residual potential in the photoreceptor during the
repeated electrophotographic process via controlling the electric
resistance of the protective layer itself and enhancement of layer
strength.
[0005] Further, it is shown that an appropriate resistance value of
the protective layer for electrophotographic photoreceptors is
10.sup.10-10.sup.15 .OMEGA.cm. Further, the surface resistance of
the photoreceptors decreases due to adhesion of corona products
such as ozone or nitrogen oxides generated during repeated
charging, particularly at high humidity, whereby problems such as
image smearing occurs. Further, releasing properties of binding
resin to realize longer life and durability against abrasion and
scratches due to sliding have not been sufficient. Subsequently, at
present, a protective layer, which exhibits targeted
electrophotographic characteristics, has not been realized.
[0006] (Patent Document 1) Japanese Patent Publication Open to
Public Inspection (hereinafter referred to as JP-A) No.
57-30846.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to provide an
electrophotographic photoreceptor which exhibits excellent film
strength, minimizes abrasion amount and forms sharp images under
high temperature and high humidity.
[0008] The above object of the present invention is achieved via
the following embodiments. [0009] 1. An electrophotographic
photoreceptor comprising an electrically conductive support having
thereon a photosensitive layer and a protective layer in that
order,
[0010] wherein the protective layer comprises a resin which is
prepared by allowing at least two acrylic or methacrylic compounds
to react with one another.
[0011] Among the acrylic or methacrylic compounds, one is a minimum
acryloyl equivalent compound having minimum acryloyl equivalent and
the other is a maximum acryloyl equivalent compound having maximum
acryloyl equivalent, the minimum acryloyl equivalent being
different from the maximum acryloyl equivalent.
[0012] The relationships 1) and 2) are satisfied;
100.ltoreq.maximum acryloyl equivalent-minimum acryloyl
equivalent.ltoreq.400 1)
0.1.ltoreq.weight of minimum acryloyl equivalent compound/weight of
maximum acryloyl equivalent compound.ltoreq.1.6. 2)
[0013] The acryloyl equivalent of an acrylic or methacrylic
compound is molecular weight of the acrylic or methacrylic
compound/number of acryloyl or acryloyl groups of the acrylic or
methacrylic compound.
[0014] The relationships 2') is satisfied in the preferable
embodiment.
0.1.ltoreq.weight of minimum acryloyl equivalent compound/weight of
maximum acryloyl equivalent compound.ltoreq.0.5. 2')
[0015] The number of acryloyl groups of the minimum acryloyl
equivalent compound is preferably at least 4.
[0016] The number of acryloyl groups of the aforesaid maximum
acryloyl equivalent compound is preferably 2.
[0017] The electrophotographic photoreceptor may prepared by a
method comprising steps of forming a photosensitive layer on an
electrically conductive support, coating a coating composition
containing at least two acrylic or methacrylic compounds dissolved
in a solvent, exposing coated composition to actinic radiation, in
which one of the acrylic or methacrylic compounds is a minimum
acryloyl equivalent compound having a minimum acryloyl equivalent
and another of the acrylic or methacrylic compounds is a maximum
acryloyl equivalent compound having a maximum acryloyl equivalent,
the minimum acryloyl equivalent being different from the maximum
acryloyl equivalent, and
[0018] relationships 1) and 2) are satisfied;
100.ltoreq.maximum acryloyl equivalent-minimum acryloyl
equivalent.ltoreq.400 1)
0.1.ltoreq.weight of minimum acryloyl equivalent compound/weight of
maximum acryloyl equivalent compound.ltoreq.1.6, 2)
[0019] wherein acryloyl equivalent of an acrylic or methacrylic
compound is
[0020] (molecular weight of the acrylic or methacrylic
compound)/(number of acryloyl or acryloyl groups of the acrylic or
methacrylic compound).
[0021] The other embodiments are described. [0022] 1. An
electrophotographic photoreceptor which comprises an electrically
conductive support having thereon a photosensitive layer and a
protective layer, which are multi-layered in this order, wherein
the aforesaid protective layer comprises a resin which is prepared
by allowing at least two (meth)acrylic compounds, which differ in
acryloyl equivalent, to react with one another, followed by curing
reaction, and in the aforesaid at least two (meth)acrylic compounds
which differ in acryloyl equivalent, relationships 1) and 2)
described below, are satisfied.
[0022] 100.ltoreq.maximum acryloyl equivalent-minimum acryloyl
equivalent.ltoreq.400 1)
0.1.ltoreq.weight of minimum acryloyl equivalent compound/weight of
maximum acryloyl equivalent compound.ltoreq.1.6 2) [0023] 2. The
electrophotographic photoreceptor, described in 1. above, wherein
in aforesaid relationships 1) and 2), 2) is 0.1.ltoreq.weight of
minimum acryloyl equivalent compound/weight of maximum acryloyl
equivalent compound.ltoreq.0.5. [0024] 3. The electrophotographic
photoreceptor, described in 1. or 2. above, wherein the number of
acryloyl groups of the aforesaid minimum acryloyl equivalent
compound is at least 4. [0025] 4. The electrophotographic
photoreceptor, described in any one of 1., 2. or 3. above, wherein
the number of acryloyl groups of the aforesaid maximum acryloyl
equivalent compound is 2.
DESCRIPTION OH THE PREFERRED EMBODIMENTS
[0026] According to the present invention, it was possible to
provide an electrophotographic photoreceptor which exhibits
excellent film strength, minimizes abrasion amount and forms sharp
images under high temperature and high humidity.
[0027] The present invention will now be detailed.
[0028] In the present invention, mechanical strength and printing
life of electrophotographic photoreceptors (hereinafter also
referred to simply as photoreceptors) are enhanced via the
protective layer formed thereon. The aforesaid protective layer
comprises a resin which is prepared by reacting photocurable
acrylic or methacrylic compounds, which are abbreviated as
"(meth)acrylic compounds". Examples of such (meth)acrylic compounds
of this invention will be listed. (Meth)acrylic compounds refer to
compounds having either an acryloyl group, (CH.sub.2.dbd.CHCO--) or
a methacryloyl group, (CH.sub.2.dbd.CCH.sub.3CO--). Further, number
of Ac groups (number of acryloyl groups), as described herein,
refers to the number of acryloyl or methacryloyl groups.
TABLE-US-00001 Exemplified Number of Compound No. Structural
Formula Ac groups (1) ##STR00001## 3 (2) ##STR00002## 3 (3)
##STR00003## 3 (4) ##STR00004## 3 (5) ##STR00005## 3 (6)
##STR00006## 4 (7) ##STR00007## 6 (8) ##STR00008## 6 (9)
##STR00009## 3 (10) ##STR00010## 3 (11) ##STR00011## 3 (12)
##STR00012## 6 (13) ##STR00013## 5 (14) ##STR00014## 5 (15)
##STR00015## 5 (16) ##STR00016## 4 (17) ##STR00017## 5 (18)
##STR00018## 3 (19) ##STR00019## 3 (20) ##STR00020## 3 (21)
##STR00021## 6 (22) ##STR00022## 2 (23) ##STR00023## 6 (24)
##STR00024## 2 (25) ##STR00025## 2 (26) ##STR00026## 2 (27)
##STR00027## 2 (28) ##STR00028## 3 (29) ##STR00029## 3 (30)
##STR00030## 4 (31) ##STR00031## 4 (32) RO--C.sub.6H.sub.12--OR 2
(33) ##STR00032## 2 (34) ##STR00033## 2 (35) ##STR00034## 2 (36)
##STR00035## 2 (37) ##STR00036## 3 (38) ##STR00037## 3
[0029] In the above formulae, R and R' are each as follows:
##STR00038##
[0030] KAYARAD MANDA (being a bifunctional acryl monomer having a
molecular weight of 312, produced by Nippon Kayaku Co., Ltd.):
C-1
[0031] Further employed by be various reactive oligomers. Examples
of usable ones include epoxyacrylate oligomer, urethane acrylate
oligomer, polyester acrylate oligomer, and unsaturated polyester
resins.
TABLE-US-00002 Exemplified Number of Compound No. Structural
Formula Ac groups (39) ##STR00039## 2 and ##STR00040## 2 (40)
(ROCH.sub.2).sub.3CCH.sub.2OCONH(CH.sub.2).sub.6NHCOOCH.sub.2C(CH.sub-
.2OR).sub.3 2 R: --COCH.dbd.CH.sub.2
[0032] Exemplified Compound (39) is E4853, produced by Daicel-Cytec
Co., Ltd.
[0033] KAYARAD DPCA 120 (being hexaacrylate of a dipentaerythritol
derivative at a molecular weight of 1,947, produced by Nippon
Kayaku Co., Ltd.): B-2
[0034] E8402 (being bifunctional urethane acrylate at a molecular
weight of 1,000, produced by Daicel-Cytec Co., Ltd.): B-3
[0035] The photoreceptor of this invention comprises an
electrically conductive support having thereon a photosensitive
layer and a protective layer. The protective layer contains a resin
which is prepared by allowing at least two (meth)acrylic compounds
to react and cure, and the compounds have different acryloyl
equivalent from each other. One is a compound having a minimum
acryloyl equivalent, that is called minimum acryloyl equivalent
compound, and the other is a compound having a maximum acryloyl
equivalent, that is called maximum acryloyl equivalent compound.
The acryloyl equivalent of an acrylic or methacrylic compound is
ratio of molecular weight to number of acryloyl or acryloyl groups
of the acrylic or methacrylic compound, that is, (molecular
weight)/(number of acryloyl or acryloyl groups) of the acrylic or
methacrylic compound. The (meth)acrylic compounds satisfy the
relationships 1) and 2).
[0036] Further, it is more preferable that 2) is 0.1.ltoreq.weight
of minimum acryloyl equivalent compound/weight of maximum acryloyl
equivalent compound.ltoreq.0.5. Still further, it is preferable
that the number of acryloyl groups of the minimum acryloyl
equivalent compound is at least 4, while it is further preferable
that the number of acryloyl groups of the maximum acryloyl
equivalent compound is 2.
[0037] The term "an acryloyl group" includes an acryloyl group and
a methacryloyl group hereafter.
[0038] Acryloyl group, as described herein, includes the group
represented by R or R', while acryloyl equivalent is defined as
molecular weight of acrylic compound/number of acryloyl groups. In
the case of oligomer, the molecular weight refers to the average
molecular weight, while the number of the acryloyl groups is the
number of the acryloyl groups in the oligomer of a maximum
molecular weight.
[0039] The inventors of the present invention discovered that when
the residual amount of the non-reacted acryloyl group in the cured
resin, unsharp image blurring is formed in an ambience of high
temperature and high humidity. On the other hand, when to decrease
the amount of acryloyl group in the film, resins are formed
employing a reactive curable materials having the smaller number of
acryloyl groups, film strength becomes insufficient, whereby during
actual image printing, the amount of the scraped photoreceptor
increases.
[0040] The inventors of the present invention discovered that by
employing a protective layer which is prepared employing
(meth)acrylic compounds which satisfy the above two relationships,
it was possible to simultaneously overcome the problem of
insufficient film strength and the problem of image blurring at
high temperature and high humidity.
[0041] The acryloyl equivalent difference and the amount ratio of
(meth)acrylic compounds having different acryloyl equivalent, will
now be described.
[0042] An object of the present invention is to realize
compatibility of high quality of sufficient film strength and sharp
images. When attention is paid to film strength, it is possible to
prepare many crosslinking points carrying film which is hard and is
not easily scraped when the protective layer is formed in such a
manner that materials exhibiting small acryloyl equivalent as
possible, namely only multi-functional materials, undergo reaction
and curing.
[0043] However, it is assumed that functional groups in the film
result in a state of markedly large steric hindrance, and are fixed
during an early period to make it impossible to realize positional
relationships among functional groups for reaction, whereby many
unreacted acryloyl groups remain in the protective layer. It is
considered that the remaining acryloyl groups are affected by the
ambience of high temperature and high humidity, as well as acidic
gases to result in image blurring.
[0044] On the other hand, in order to form sharp images, compounds
which exhibit as large acryloyl equivalent as possible are
advantageously employed, while it is not possible to realize the
targeted enhancement of film strength. In the present invention, it
is assumed that reaction rate in the film is enhanced in such a way
that polyfunctional compounds of smaller acryloyl equivalent are
employed at a crosslinking branch point, and between the above
points, a mixture, which is prepared by mixing at an appropriate
ratio, low functional compounds of large acryloyl equivalent, which
exhibit a relatively large degree of freedom in terms of structure,
undergoes reaction.
[0045] By controlling the acryloyl equivalent and the amount ratio
within the specified value as described, residual acryloyl groups
were successfully and significantly decreased, and targeted film
strength and sharp images were simultaneously realized. Namely, it
was discovered that targeted film strength and sharp images were
simultaneously realized by employing at least two (meth)acrylic
compounds, which differed in acryloyl equivalent, so that these
satisfy above relationships 1) and 2).
[0046] The other resins may be blended in addition to at least two
(meth)acrylic compounds having different acryloyl equivalent each
other in the present invention. Examples of the resins include
polyester, polycarbonate, polyurethane, acrylic resins, epoxy
resins, silicone resins, alkyd resins, or vinyl chloride-vinyl
acetate copolymers.
[0047] A polymerization initiator may be employed for curing
reaction of (meth)acrylic compounds. The added amount of the
initiators is preferably 0.1-20% with respect to the total weight
of the (meth)acrylic compounds, but is more preferably 0.5-10%.
Usable initiators include photopolymerization initiators and
thermal polymerization initiators. Further, both may be employed in
combination.
[0048] The protective layer of the present invention is formed in
such a manner that at least two (meth)acrylic compounds, which
differ in acryloyl equivalent, are dissolved in solvents and the
resulting liquid coating composition is coated followed by
undergoing reaction. The protective layer may also be formed in
such a manner that a liquid coating composition in which, other
than the above (meth)acrylic compounds, if desired, polymerization
initiators, fillers, lubricant particles and antioxidants may be
incorporated, and is coated followed by undergoing reaction. A
preferred protective layer is formed in such a manner that a liquid
coating composition into which the above (meth)acrylic compounds
and fillers (such as minute electrically conductive metal oxide
particles) are dispersed, is coated, followed by undergoing
reaction.
[0049] When the (meth)acrylic compounds of the present invention
undergo reaction, methods are employed which include a method in
which reaction undergoes via electron cleavage, and a method in
which radical polymerization initiators are added and reaction is
performed via radiation and heat. Employed as the polymerization
initiators may be any of the photopolymerization initiators and
thermal polymerization initiators. Further, a photopolymerization
initiator and a thermal polymerization initiator may be employed in
combination.
[0050] Polymerization initiators include acetophenone based or
ketal based photopolymerization initiators such as
diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one,
1-hydroxy-cyclohexyl-phenyl-ketone,
4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone,
2-benzyl-2-dimethylamino-1-(4-morphlinophenyl)butanone-1,2-hydroxy-2-meth-
yl-1-phenylpropane-1-one,
2-methyl-2-morpholino(4-methylthiophenyl)propane-1-one, or
1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime; benzoinether
based photopolymerization initiators such as benzoin, benzoin
methyl ether, benzoin isobutyl ether, or benzoin isopropyl ether;
benzophenone based photopolymerization initiators such as
benzophenone, 4-hydroxybenzophenone, methyl o-benzoyl benzoate,
2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoyl phenyl ether,
acrylated benzophenone, or 1,4-benzoylbenzene; and thioxanthone
based photopolymerization initiators such as
2-isopropylthioxanthone, 2-chlorothioxanthone,
2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, or
2,4-dichlorothioxanthone.
[0051] Other photopolymerization initiators include
ethylanthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide,
2,4,6-trimethylbenzoylphenylethoxyphosphine oxide,
bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide,
bis(2,4-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide,
methylphenyl glyoxyester, 9,10-phenantholene, acridine based
compounds, triazine based compounds, and imidazole based compounds.
Further, compounds which exhibit photopolymerization enhancing
effects may be employed individually or in combination with the
above photopolymerization initiators. Examples of such include
triethanolamine, methyldiethanolamine, ethyl
4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate,
(2-dimethylamino)ethyl benzoate, and
4,4'-dimethylaminobenzophenone.
[0052] These polymerization initiators may be employed individually
or in combinations of at least two types. The content of
polymerization initiators is commonly 0.1-20 parts by weight with
respect to 100 parts by weight of the (meth)acrylic compounds, and
is preferably 0.5-10 parts by weight.
[0053] Further, in order to enhance film strength and to control
resistance, incorporated may be various fillers. Usable fillers
include various metal oxides such as silica, alumina, zinc oxide,
titanium oxide, tin oxide, antimony oxide, indium oxide, or bismuth
oxide, as well as ultra-fine particles such as tin-doped indium
oxide, antimony-doped tin oxide and zirconium oxide. These metal
oxides may be employed individually or in combinations of at least
two types. When employed in combinations, states such as solid
solution or fusion may be acceptable.
[0054] The diameter of filler particles is preferably 1-300 nm in
terms of number average primary particle diameter, but is most
preferably 3-100 nm. The ratio of fillers in the protective layer
is preferably 1-100 parts by weight with respect to 100 parts by
weight of the binder resin, but is most preferably 10-80 parts by
weight.
[0055] In the protective layer employed in the present invention,
to enhance dispersibility of minute electrically conductive metal
oxide particles and to enhance smoothness, various additives may be
incorporated. Specifically, with regard to enhancement of
dispersibility, it is very effective to perform a surface treatment
employing minute metal oxide particles. Surface treatments include
treatments with various inorganic compounds, and treatments with
silicon compounds, fluorine-containing silane coupling agents,
fluorine-modified silicone oils, fluorine-containing surface active
agents, and fluorine-based graft polymers.
[0056] Various lubricating particles may be incorporated into the
protective layer employed in the present invention. For example,
fluorine containing resin particles may be incorporated. Fluorine
containing resin particles may be composed of tetrafluoroethylene
resins, trifluoromonochloroethylene resins,
hexafluoromonochloroethylene propylene resins, vinyl fluoride
resins, vinylidene fluoride resins, or difluorodichloroethylene
resins, and copolymers thereof. It is preferable that they are
employed individually or in combinations at least two types upon
appropriately selected. Specifically preferred are
tetrafluoroethylene resins and vinylidene fluoride resins. The
ratio of fluorine containing resin particles in the protective
layer is in the range of 5-70% by weight, but is more preferably in
the range of 10-60% by weight. The diameter of lubricating
particles is preferably 0.01-1 .mu.m in terms of average primary
particle diameter, but is most preferably 0.05-0.5 .mu.m. The
appropriate molecular weight of resins and the diameter of
particles may be selected, and but not particularly limited.
[0057] Usable means to disperse fillers and lubricating particles
include, but are not limited to, an ultrasonic homogenizer, a ball
mill, a sand grinder, and a homomixer.
[0058] In the present invention, in order to enhance weather
resistance, incorporated into the above protective layer may be
additives such as antioxidants. Antioxidants which are the same as
those incorporated in the charge transporting layer may be
selected.
[0059] Solvents to form the protective layer include, but are not
limited to, methanol, ethanol, n-propyl alcohol, isopropyl alcohol,
n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene,
methylene chloride, methyl ethyl ketone, cyclohexane, ethyl
acetate, butyl acetate, methyl cellosolve, ethyl cellosolve,
tetrahydrofuran, 1-dioxane, 1,3-dioxolan, pyrimidine, and
diethylamine.
[0060] It is preferable that the protective layer of the present
invention, after coating, is subjected to natural drying or heat
drying, followed by reaction via exposure to actinic radiation.
[0061] Employable coating methods include those known in the art,
such as a dip coating method, a spray coating method, a spinner
coating method, a bead coating method, a blade coating method, a
beam coating method, or a slide hopper method, which are described
as a coating method for the interlayer and the photosensitive
layer.
[0062] It is preferable that the coated layer of the photoreceptor
of the present invention is cured while forming cured resins in
such as manner that actinic radiation is exposed to the coating to
generate radicals followed by polymerization and curing is
performed by formation of crosslinking bonds via inter- and
intramolecular crosslinking reactions. Ultraviolet radiation and
electron beams are particularly preferred as the above actinic
radiation.
[0063] Usable ultraviolet radiation sources are not particularly
limited as long as they generate appropriate ultraviolet radiation.
For example, employed may be low pressure mercury lamps, medium
pressure mercury lamps, high pressure mercury lamps, ultra-high
pressure mercury lamps, carbon arc lamps, metal halide lamps, and
xenon lamps. Exposure conditions differ depending on each type of
lamp. The exposure amount of actinic radiation is commonly 5-500
mJ/cm.sup.2, but is preferably 5-100 mJ/cm.sup.2. Power consumption
of the above lamps is preferably 0.1-5 kw, but is most preferably
0.5-3 kw.
[0064] In regard to electron beams, electron beam exposure devices
are not particularly limited. Commonly employed as an electron beam
accelerator for electron beam exposure is one of the curtain beam
system, which is relatively low cost, and results in high output.
Acceleration voltage during exposure to electron beams is
preferably 100-300 kV, while the absorption dose is preferably
0.5-10 Mrad.
[0065] Exposure period to reach the exposure amount of necessary
active radiation is preferably 0.1 second-10 minutes, but in view
of curing efficiency of (meth)acrylic compounds and operating
efficiency, is more preferably 0.1 second to 5 minutes.
[0066] Ultraviolet radiation is particularly preferred as actinic
radiation due to ease of use.
[0067] The photoreceptor of the present invention may be dried
prior to and after exposure of actinic gradation, and during
exposure of actinic radiation, and timing to carry out drying may
be appropriately selected depending on these combinations.
[0068] Appropriate drying conditions are selected depending on the
type of solvents and film thickness. Drying temperature is
preferably between room temperature--180.degree. C., but is most
preferably 80-140.degree. C., while drying period is preferably
1-200 minutes, but is most preferably 5-100 minutes.
[0069] A protective layer is preferably formed in such a manner
that minute electrically conductive metal oxide particles are
dispersed into the above binder resins, and the resulting
dispersion is coated, followed by curing. The thickness of the
protective layer is preferably 0.2-10 .mu.m, but is more preferably
0.5-6 .mu.m.
[0070] A photosensitive layer will now be described.
[0071] The photoreceptor of the present invention comprises an
electrically conductive support having thereon at least a
photosensitive layer and a protective layer. The layer
configurations are not particularly limited and include the
following specific ones:
[0072] 1) Provided on an electrically conductive support are charge
generating and charge transporting layers as a photosensitive
layer, and a protective layer in the stated order.
[0073] 2) Provided on an electrically conductive support are a
single layer incorporating charge transporting and charge
generating materials as a photosensitive layer, and a protective
layer in the stated order.
[0074] 3) Provided on an electrically conductive support are an
interlayer, charge generating and charge transporting layers as a
photosensitive layer, and a protective layer in the stated
order.
[0075] 4) Provided on an electrically conductive support are an
interlayer, a single layer incorporating charge transporting and
charge generating materials as a photosensitive layer, and a
protective layer in the stated order.
[0076] The photoreceptor of the present invention may be composed
of any of the above layer configurations, but of these, one is
preferred which is produced via providing, on an electrically
conductive support, an interlayer, a charge generating layer, a
charge transporting layer, and a protective layer.
[0077] It is possible to coat these interlayer, photosensitive
layer and protective layer, employing coating methods such as a dip
coating method, a spray coating method, a spinner coating method, a
bead coating method, a blade coating method, a beam coating method,
or a slide hopper coating method.
(Electrically Conductive Supports)
[0078] Supports employed in the present invention are not
particularly limited as long as they are electrically conductive,
and examples include those which are produced by molding metals
such as aluminum, copper, chromium, nickel, zinc, or stainless
steel into a drum or a sheet, by laminating metal foil composed of
aluminum or copper onto a plastic film, or by depositing aluminum,
indium oxide, or tin oxide onto a plastic film, as well as metal,
plastic film and paper provided with an electrically conductive
layer which is prepared via coating electrically conductive
materials individually or in combination with binder resins.
(Interlayer)
[0079] In the present invention, it is possible to provide, between
the electrically conductive layer and the photosensitive layer, a
sublayer exhibiting a barrier function and an adhesion function. It
is possible to form the sublayer in such a way that binders, such
as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid
copolymer, polyamide, polyurethane, or gelatin, are dissolved in
solvents, followed by application of the resulting composition via
dip coasting. Of these, preferred is a polyamide which is soluble
in alcohol.
[0080] Further, to control resistance of the interlayer, various
minute electrically conductive particles and metal oxides may be
incorporated. Examples include various metal oxides such as
alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide,
indium oxide, or bismuth oxide. It is possible to employ ultra-fine
particles such as indium oxide doped with tin, as well as tin oxide
and zirconium oxide doped with antimony. These metal oxides may be
employed individually or in combinations of at least two types.
When employed in combinations of at least two types, states such as
solid solution or fusion are acceptable. The average diameter of
the above metal oxide particles is preferably at most 0.3 .mu.m,
but is more preferably at most 0.1 .mu.m.
[0081] Preferred solvents employed to form the interlayer are those
which efficiently disperse inorganic particles and dissolve
polyamide resins. Specifically preferred are alcohols having 2-4
carbon atoms, such as ethanol, n-propyl alcohol, isopropyl alcohol,
n-butanol, t-butanol, or sec-butanol, since they exhibit high
solubility of polyamide resins and excellent coating properties.
Further listed as solvent aids which result in the targeted effects
in combination with the above solvents to enhance retention
properties and particle dispersibility, are methanol, benzyl
alcohol, toluene, methylene chloride, cyclohexane, and
tetrahydrofuran.
[0082] Concentration of binder resins is appropriately selected to
match to the thickness of the interlayer and the production rate.
The mixing ratio of inorganic particles to binder resins during
dispersing of inorganic particles is preferably 20-400 parts by
weight with respect to 100 parts by weight of the binder resins,
but is more preferably 50-200 parts.
[0083] Employed as inorganic particle dispensing means may be an
ultrasonic homogenizer, a ball mill, a sand grinder, and a
homomixer, however the means are not limited thereto.
[0084] Appropriate drying methods of the interlayer may be selected
depending on the type of solvents and the film thickness, but heat
drying is preferred.
[0085] The thickness of the interlayer is preferably 0.1-15 .mu.m,
but is more preferably 0.3-10 .mu.m.
[0086] The charge generating layer employed in the present
invention comprises a charge generating material and binder resin.
It is preferable that the above charge generating layer is formed
in such a way that charge generating material is dispersed into a
binder resin solution and the resulting dispersion is coated.
(Charge Generating Layer)
[0087] Examples of preferably employed binders of the charge
generating layer include polystyrene resins, polyethylene resins,
polypropylene resins, acrylic resins, methacrylic resins, vinyl
chloride resins, vinyl acetate resins, polyvinyl butyral resins,
epoxy resins, polyurethane resins, phenol resins, polyester resins,
alkyd resins, polycarbonate resins, silicone resins, and melamine
resins, as well as copolymer resins incorporating at least two of
the above resins (for example, vinyl chloride-vinyl acetate
copolymer resins and vinyl chloride-vinyl acetate-maleic anhydride
copolymer resins) and polyvinyl carbazole resins.
[0088] It is preferable to form the charge generating layer as
follows. Charge generating materials are dispersed, via a
homogenizer, into a solution prepared by dissolving binder resins
into solvents, whereby a liquid coating composition is prepared.
The resulting liquid coating composition is coated via a coater to
result in a predetermined thickness and the coating is then
dried.
[0089] Preferably employed solvents which dissolve binders employed
in the charge generating layer for coating include toluene, xylene,
methylene chloride, 1,2-dichloroethane, methyl ethyl ketone,
cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol,
propanol, butanol methyl cellosolve, ethyl cellosolve,
tetrahydrofuran, 1-dioxane, 1,3-dioxyolane, pyridine and
diethylamine.
[0090] Employed as dispersing means of charge generating materials
may be an ultrasonic homogenizer, a ball mill. a sand grinder, and
a homomixer.
[0091] The ratio of charge generating materials to binder resins is
preferably 20-600 parts by weight with respect to 100 parts by
weight of the binder resins, and is more preferably 50-500 parts.
The thickness of the charge generating layer, though varying
depending on targeted characteristics of charge generating
materials and binder resins, as well as on the mixed ratio of
resins, is preferably at most 5 .mu.m, is more preferably 0.01-5
.mu.m, but is still more preferably 0.05-3 .mu.m. Meanwhile, it is
possible to minimize image problems via filtering the charge
generating layer liquid coating composition prior to coating to
remove foreign matter and coagulants. It is also possible to carry
out formation via vacuum deposition of the above pigments.
(Charge Transporting Layer)
[0092] A charge transporting layer employed in the photoreceptor of
the present invention comprises charge transporting materials and
binder resins, and is formed in such a manner that the above charge
transporting materials are dissolved in the above binder resins and
the resulting mixture is coated. Examples of charge transporting
materials include carbazole derivatives, oxazole derivatives,
oxadiazole derivatives, thiazole derivatives, thiadiazole
derivatives, triazole derivatives, imidazole derivatives,
imidazolone derivatives, imidazolidine derivatives,
bisimidazolidine derivatives, styryl compounds, hydrazone
compounds, pyrazoline compounds, oxazolone derivatives,
benzimidazole derivatives, quinazoline derivatives, benzofuran
derivatives, acridine derivatives, phenazine derivatives,
aminostilbene derivatives, triarylamine derivatives,
phenylenediamine derivatives, stilbene derivatives,
poly-N-vinylcarbazole, poly-1-vinylpyrene, and
poly-9-vinylanthracene. At least two of them are blended and then
employed.
[0093] Examples of binders for the charge transporting layer
include polycarbonate resins, polyacrylate resins, polyester
resins, polystyrene resins, styrene-acrylonitrile copolymer resins,
polymethacrylate resins, and styrene-methacrylate copolymer resins,
of which polycarbonate is preferred. Further, in terms of cracking
resistance, abrasion resistance and charging characteristics,
preferred are EPA, BPZ, dimethyl EPA, and BPA-dimethyl EPA
copolymers.
[0094] It is preferable to form the charge transporting layer in
such a manner that binder resins and charge transporting materials
are dissolved in solvents and the resulting liquid coating
composition is applied onto a substrate to result in uniform layer
thickness, followed by drying the coating.
[0095] Examples of solvents employed to dissolve the above binder
resins and charge transporting materials include, but are not
limited to, toluene, xylene, methylene chloride,
1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl
acetate, butyl acetate, ethanol, propanol, butanol,
tetrahydrofuran, 1,4-dioxane, 1,3-dioxolan, pyridine, and
diethylamine.
[0096] The mixing ratio of charge transporting layer to binder
resins is preferably 10-500 parts by weight with respect to 100
parts by weight of the binder resins, but is more preferably 20-100
parts by weight.
[0097] Antioxidants, electronic conductors, and stabilizers may be
incorporated in the charge transporting layer. Preferably employed
as the above antioxidants may be those described in JP-A No.
2000-305291, while preferably employed as the above electronic
conductors may be those described in JP-A Nos. 50-137543, 58-76483
and so on.
[0098] The thickness of the charge transporting layer, though
variable depending on characteristics of charge transporting
materials and binder resins as well as their mixing ratio, is
preferably 5-40 .mu.m, but is more preferably 10-30 .mu.m.
[0099] The electrophotographic photoreceptor of the present
invention is not only applied to electrophotographic copiers but
also widely used in electrophotography applied fields such as
laser-beam printers, CRT printers, LED printers, liquid crystal
printers or laser plate production.
EXAMPLES
[0100] The present invention will now be detailed with reference to
examples, however the present invention is not limited thereto.
Example 1
(Preparation of Electrophotographic Photoreceptor)
(Surface Treatment of Particles: Preparation of Particles 1)
[0101] Dissolved and dispersed in 10 parts of ethanol/n-propyl
alcohol/THF (at a volume ratio of 45:20:35) was 0.2 part of methyl
hydrogen polysiloxane. After adding, to the above mixed solvents,
3.5 parts of rutile type titanium oxide (at a number average
diameter of the primary particle of 35 nm and 5% primary surface
treatment via alumina), stirring was carried out for one hour and
surface treatment (being a secondary surface treatment) was carried
out. After separation from the solvents, heat drying was carried
out, whereby Surface Treated Particles 1 were prepared.
(Interlayer)
[0102] While stirring, one part of binder resin (N-1) was dissolved
in 20 parts of ethanol/n-propyl alcohol/THF (at a volume ration of
45:20:35). Thereafter, the resulting solution was blended with 4.2
parts of Surface Treated Particles 1 and the resulting mixture was
dispersed employing a bead mill. The above dispersion was carried
out under such conditions that the average diameter of beads was
0.1-0.5 mm, the peripheral rate was set at 4 m/second, and the
retention period was three hours, whereby an interlayer liquid
coating composition was prepared. After filtration via a 5 .mu.m
filter, the resulting interlayer coating composition was applied
onto a washed cylindrical aluminum substrate (which had been
subjected to cutting work to result in 10-point surface roughness
Rz of 0.81 .mu.m, specified in JIS B 0601), employing a dip coating
method, whereby an approximately 2 .mu.m thick dried interlayer was
formed.
##STR00041##
(Charge Generating Layer)
[0103] The following components were blended and then dispersed
employing a sand mill homogenizer, whereby a charge generating
layer liquid coating composition was prepared. The resulting liquid
coating composition was applied onto the above interlayer employing
a dip coating method, whereby a 0.3 .mu.m dried charge generating
layer was formed.
TABLE-US-00003 Y-titanylphthalocyanine (being Titanylphthalocyanine
20 parts pigment, having a maximum diffraction peak at Bragg angle
(2.theta. .+-. 0.2.degree.) in an X-ray diffraction spectra by
Cu-K.alpha. characteristic X-ray Polyvinyl butyral (BX-1, produced
by Sekisui Chemical 10 parts Co., Ltd.) Methyl ethyl ketone 700
parts Cyclohexanone 300 parts
(Charge Transporting Layer)
[0104] The following components were blended and dissolved, whereby
a charge transporting layer liquid coating composition was
prepared. The resulting coating liquid was applied onto the above
charge generating layer employing a dip coating method, and then
dried at 120.degree. C. for 70 minutes to form a 20 .mu.m dried
charge transporting layer.
TABLE-US-00004 Charge transporting layer (having the following
structure) 50 parts Polycarbonate resin "IUPILON-Z300" (produced by
100 parts Mitsubishi Gas Chemical Company INC.) Antioxidant
2,6-di-t-butyl-4-methylphenol 8 parts Tetrahydrofuran/toluene
(volume ratio 8/2) 750 parts Charge transporting material
##STR00042##
(Protective Layer)
<Preparation of Protective Layer Liquid Coating
Composition>
[0105] Curable Materials A, B, and C described in Table 1 at the
volume ratio (A/B/C) described in Table 1 were dissolved in a
mixture of 5.1 parts of 1-propanol and 2.4 parts of methyl isobutyl
ketone. Further, 0.6 part of minute fluororesin particles of a
particle diameter of approximately 300 nm and 0.8 part of minute
anatase type titanium oxide particles (of a particle diameter of
approximately 6 nm and 20% by weight of surface treatment methyl
hydrogen silicone oil) were added, and the resulting mixture was
dispersed for 15 minutes employing an ultrasonic homogenizer,
whereby a dispersion incorporating curable materials, minute
fluororesin particles, and minute titanium oxide particles was
prepared. Added to the above dispersion was 0.05 part of radical
polymerization initiator (Compound D), whereby a protective layer
liquid coating composition was prepared.
##STR00043##
<Coating and Curing of Protective Layer>
[0106] The above protective layer liquid coating composition was
applied onto the aforesaid photosensitive layer via dip coating.
After application, the resulting coating was dried at room
temperature for 10 minutes. Thereafter, a photosensitive drum was
positioned 100 mm apart from a 2 kw high pressure mercury lamp, and
while rotating the above photosensitive drum, the protective layer
was cured over three minutes via exposure to radiation. After
curing, drying was carried out at a heating temperature of
120.degree. C. for 30 minutes, whereby an electrophotographic
photoreceptor provided with a protective layer was produced. In
Tables 1 and 2, Ac equivalent represents acryloyl equivalent and
weight ratio represents weight of minimum acryloyl equivalent
compound/weight of maximum acryloyl equivalent compound, while Ac
based compound refers to an acrylic compound. Ac equivalent
difference refers to the value of maximum acryloyl
equivalent-minimum acryloyl equivalent.
TABLE-US-00005 TABLE 1 Curing Material A Curing Material B Curing
Material C Molecular Number of (Meth)acrylic Molecular Number of
(Meth)acrylic Molecular Number of *1 (Meth)acrylic Weight Ac groups
*2 Compound Weight Ac groups *2 Compound Weight Ac groups *2 1 30
466 4 116.5 39 442 2 221 -- -- -- -- 2 30 466 4 116.5 39 442 2 221
-- -- -- -- 3 30 466 4 116.5 39 442 2 221 -- -- -- -- 4 30 466 4
116.5 B-2 1947 6 324.5 -- -- -- -- 5 30 466 4 116.5 B-2 1947 6
324.5 -- -- -- -- 6 30 466 4 116.5 B-2 1947 6 324.5 -- -- -- -- 7
40 764 6 127.3 B-3 1000 2 500 -- -- -- -- 8 40 764 6 127.3 B-3 1000
2 500 -- -- -- -- 9 40 764 6 127.3 B-3 1000 2 500 -- -- -- -- 10 30
466 4 116.5 39 442 2 221 C-1 312 2 156 11 30 466 4 116.5 39 442 2
221 -- -- -- -- 12 30 466 4 116.5 39 442 2 221 -- -- -- -- 13 40
764 6 127.3 B-2 1000 2 500 -- -- -- -- 14 40 764 6 127.3 B-2 1000 2
500 -- -- -- -- 15 no protective layer 16 30 466 4 116.5 40 764 6
127.3 -- -- -- -- 17 7 547 6 91.2 B-2 1000 2 500 -- -- -- -- *1:
Electrophotographic Photoreceptor No., *2: Acryloyl Equivalent
TABLE-US-00006 TABLE 2 AC Electrophotographic Equivalent Weight
Ratio Weight Photoreceptor No. Difference A/B/C Ratio 1 104.5 1/9/0
0.111 2 104.5 3/7/0 0.428 3 104.5 6/4/0 1.5 4 208 1/9/0 0.111 5 208
3/7/0 0.428 6 208 6/4/0 1.5 7 372.6 1/9/0 0.111 8 372.6 3/7/0 0.428
9 372.6 6/4/0 1.5 10 104.5 3/6/1 0.5 11 104.5 0.5/9.5/0 0.0526 12
104.5 6.5/3.5/0 1.857 13 372.6 0.9/9.1/0 0.0989 14 372.6 6.5/3.5/0
1.857 15 no protective layer 16 10.8 3/7/0 0.428 17 408.8 2/8/0
0.25
[0107] Ac Based compounds 7, 30, 39, and 40 in Table 1 are each the
above exemplified compounds.
[0108] B-2: KAYARAD DPCA120 (hexaacrylate of hexafunctional
dipentaerythritol derivative, of a molecular weight of 1947,
produced by Kippon Kayaku Co., Ltd.)
[0109] B-3E8402 (bifunctional urethane acrylate of a molecular
weight of 1,000, produced by Daicel-Cytec Co., Ltd.)
[0110] C-1 KAYARAD MANDA (bifunctional monomer of a molecular
weight of 312, produced by Nippon Kayaku Co., Ltd.)
(Evaluation)
[0111] Each of the electrophotographic photoreceptors listed in
Table 1 was mounted on MAGIC COLOR 5430 (Konica Minolta Business
Technologies, Inc.), and the following evaluation items were
evaluated.
(Image Blurring)
[0112] At an ambience of temperature/humidity of 30.degree. C./85%,
5% printing images were continually printed onto 10,000 sheets.
After turning off the power source, the printer was allowed to
stand at the above ambience for 12 hours. After 12 hours, the
printer was turned on, and image blurring was evaluated. [0113] A:
no image blurring was noted [0114] B: negligible image blurring
occurred [0115] C: slight image blurring occurred but was at a
commercially viable level [0116] D: image blurring occurred often
and was at a commercially unviable level
(Photoreceptor Scraping (Abrasion Degree))
[0117] After printing the above 10,000 sheets, the thickness of the
photoreceptor prior to and after printing was determined, and the
abrasion degree of the photoreceptor was determined.
TABLE-US-00007 TABLE 3 Photoreceptor Electrophotographic Image
Abrasion Photoreceptor No. Blurring Degree (.mu.m) 1 A 0.8 2 A 0.3
3 B 0.15 4 B 1.7 5 B 0.9 6 B 0.7 7 A 1.9 8 A 1 9 B 0.7 10 A 0.4 11
B 3.2 12 D 0.1 13 A 4 14 D 0.2 15 B 3 16 D 0.24 17 C 2.9
[0118] As can be seen from Table 3, electrophotographic
photoreceptors of the present invention resulted in good evaluation
of image blurring and low photoreceptor abrasion. On the other
hand, comparative electrophotographic photoreceptors resulted in no
better evaluation of both criteria.
* * * * *